Yin Yoga and Qigong both operate under Chinese Medicine Theories.
Where meridian channels are stimulated to restore, balance & strengthen Qi flow within our bodies as a means of igniting the body's ability to self-heal (where "Qi" refers to our inner 'vital energy' that exists inside everyone & inside of everything thing).
According to Chinese Medicine, Qi can be stimulated, restored or strengthened FOUR ways:
Acupuncture,
Breath work,
Visualisation, &
Traction &/or compression of the Yin connective tissues (our fascia - joints, ligaments, bones, & everything else making up the body).
In Qigong and Yin Yoga we stimulate Qi in three out of the four possible ways. This means via Qigong & Yin Yoga practices we are able to effectively strengthen & nourish our Qi energy system that is responsible for our emotional & physical wellbeing. Impressive!
According to Chinese Medicine Theory we have 12 main meridian channels within our bodies, acting like river passage ways that transport Qi (aka. life-force energy), blood (loaded with nutrients & oxygen) & other bodily fluids throughout body. Each Yin pose or Qigong exercise targets Qi flow & balance within specific meridian channels allowing us to selectively ease a range of associated physical or emotional complaints that we may be enduring - anything from having a tendency towards being quick to anger or easily frustrated, to constant worry about what others think, feeling fatigued or even something more serious like healing injured body tissues.
Yin Yoga and Qigong both involve meditation with movement.
Achieving a meditative state can be easier relative to a situation where you just sat in stillness as the movement or sensations of the body can help give your mind something to focus on bringing you into the present moment.